1. Field of the Invention
This invention relates to a gear system. More specifically, the invention relates to an internal gear pair system, e.g. in a planetary gear system.
2. Discussion of the Prior Art
Planetary or epicyclic gear systems for use in speed reducers are by no means new. Examples of such systems are described in U.S. Pat. Nos. 546,249, issued to D. S. Regan on Sep. 10, 1895; 1,693,154, issued to J. Newmann on Nov. 27, 1928; 2,037,787, issued to J. W. Hughes on Apr. 21, 1936; 2,049,696, issued to E. A. M. Fliesberg on Aug. 4, 1936; 2,250,259, issued to B. Foote, Jr. on Jul. 22, 1941 and 5,277,672, issued to Droulon et al on Jan. 11, 1994.
One application of an internal gear pair system is in a planetary gear system. The basic elements of a planetary gear system include an internal gear, which is an annular gear, and a pinion, which is a gear with a smaller number of teeth than the internal gear. When the pinion is driven, the teeth thereof mesh with the teeth of the internal gear for driving the latter. When producing internal gear pair systems two of the main problems to be considered are (i) interference between the tips of the gear teeth and (ii) good contact between the gear teeth to ensure maximum torque transmission. It is also sometimes desirable to be able to make the tooth ratio as close as possible to one. To do so the difference in the number of teeth on the pinion and the internal gear must be a minimum. Ideally, it should be possible to reduce the difference between the number of teeth on the internal gear and the pinion to one. Common problems in such gear pair systems are tip interference and limited contact between the teeth of the gears.